Variable electrical condenser



April 5.1927

L. R. MQDONALD VARIABLE ELECTRICAL CONDENSER Filed March 7, 1924 avwcntoz 351 k 10 abhor nu;

f meats are'particularly directed to improved F accurate adjustment with a minimum of dis- -UNITED. STA

Patented Apr. 5, 1927;.

TES

Bt McDONALD. or wns'rmorm'r. comma. cinema;

VARIABLE ELECTRICAL CONDENSER 1 Annotation filed Emma i. 19: 4.2 semnumsaziiii.

'Myinvention relates-to that class or va -=riahlefelectrical condensers which ma be j designated as micrometer condensers, w 1ereby a very high degree of accuracy of ad-.

justment may he obtained; and'm'y mprovemeansfor permitting and insuring highly turhance from outsidefinfluences.

" In the drawings Figzil'is an. elevation of an embodiment of my improved condenser;

Fig. 2 is an end View of thesame, lookin view 'taken as on the line'-l-t Fig.-

to the rightomFig. l,'the-mounting.pane be'ngomitted; Fig. 3 is'a 'lougitudlual :'ec-' tional mewyand Fig. 4 1s acres; sectional V lookin to the right.

Simiiar: parts .are designated by corresponding reference numerals in"all the tiguros v v The body 1 of the. condenser is formed of suitable conductive material such as brass or the like, and isprovided with a suitable shank 'or extension 2 for conveniently attaching it within a casing of insulating material 3, as by nuts 4, 53, which also serve for eonncctmg it with n hue wire.

The opposite. end of the body 1 is provided with a reduced portion or shank (3. A cylindrical body 7, of suitable dielectric material, is molded or. mounted upon the shank 6,. so

as to be held thereby, the diameter of thecylindcr I being slightly greater than that of'the body 1.

A tube 8, of suitable conductive material such as brass, is bored to lit accurately over the cylinder 7, prmrtically without lateral play, but so as to xermit -jiongitudinal telescoping movement la.-t\\'-."en"-'thc tube and cvlinder. screw thread 9, the fineness and the. pitch of which are governed by the desired accuracy of adjustment.

The tube 8 is provided with it suitable air went, as 10; and the tube is also provided with suitable means, as nuts and 16 for the attachment. of a line wire. T lie-tension 'm'entby'sliding itfto L I conductor LZQwhich niay-fbe followed-Q10 Ll'ide across/the thread. aft

' the thread 9 to travel- The exterior of the tube carries a -ot the spr n w-ma ia-th r sf 'mpms rfl sprang.- llns arrange eat le conta'ct 1 lzetiyeerif th' mlie js, the e nda tqrfli ielilifig to permit the tube, or fro; on I the =d1 lectrjc' ijior,. appi name Adjuster 'inent is luarfected rob m i re: na etadiuezs irogmstlthe spring 3 swea reward or back imder the end of rthe. conductor 12 jimtilgthe'idej sired degree of adjnstment has been phtainedfg The. longitudinal movement of the tube 8 relative to the body vl, varies the influence of the dielectric'i,.aud also varies the influence of the atmospheric dielectric lying rtion of the between thehody l and the tube 8 which may be surroun ing it, so that a veryreiim-d degree of adjustmeutinay be obtained. This may lie-assisted also by the use of a suitable lubricant suichas vaseli'ne,

whieh will increase the smoothness of movement between the tube 8 and itssupporting dielectric, and may also, with advantage, he applied over the body 1.

It will be understood that the embodiment of my invention which I haveillustmted and described is to' be regarded as a typical and notas an exclusive form. For it is obvious that details of construction may he modified, as by the use of mechanical equivalents. or the like, without departing from the spirit of my invention as, claimed.

Having thus described my invention, what I claim and desiieto secure by Letters latcut of the. United States is combination of relatively telcscopable and rotatable conducting elements, an lnterposed dielectric, and connecting. means mamtaining an unbroken contact with. one of said elements for causing rotation of such element. to produce longitudinal adjustment thereof, and also automatically permitting free longitudinal adjustment of such elements,

' 2. In a variable electrical condenser, the

combination, within a body of non-conductin a variable electrical eondensenrtheing material, of a fixed, cylindrical conductor, a tubular conductor sliding longitudinally outside of the cylindrical conductor and provided with an exterior screw thread, a connector projecting thrbu h said body and having a terminal. yieldflmly engaging with said screw thread to cause said tubular conductor to move longitudinally when rotated, and optionally permitting free, longitudinal movement of the conductor, and a dielectric interposed between the conductors.

3. In a rariable electrical condenser, the eombinationof a cylindricalconductor, a tubular conductor sliding longitudinally outside of the cylindrical conductor and provided with an exterior screw thread,-a spring connector, having its free end normally engaging with the screw thread to cause longitudinal adjustment of the tubular conductor by rotation thereof, said connector being yieldable to permit optional longitudinal movement of the tubular conductor past the connector, and a dielectric interposed between the conductors.

4. In a variable electrical condenser, the combination of a cylindrical conductor, a tubular conductor sliding longitudinally outside of the cylindrical conductor and provided with an exterior screw thread, :1

spring connector, having its free end nor- .mally engaging with the screw thread to cause longitudinal adjustment of the tubular conductor by rotation thereof, said connector being yieldable to ermit optional longitudinal movement of the tubular conductor past the connector, and a dielectric interposed between the conductors and serving as a guide for the tubular conductor. 4 5. In a variable electrical condenser, the combination of a cylindrical conductor, a cylindrical dielectric carried thereby, a tubular conductor, slidable longitudinally over and guided by the dielectric, and provided with a screw thread upon its outer surface, a yieldable connector having its free end normallyengaging with the screw thread.

6. In a variable-electrical condenser, the combination of a cylindrical conductor, a cylindrical dielectric of sli htly larger diameter than the body of sue conductor carried thereby, a tubular conductor sliding longitudinally over the dielectric, and prorided with an exterior screw thread, and a spring connector having its freeend normally engaging with said screw thread.-

- l LESLIE B. MCDONALD. 

